Automatic telephone system



E. JACOBSEN.

AUTCMAHC TELEPHONE SYSTEM.

APPLICATION FILED MAY 4. I918.

Patented July 6, 1920.

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AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED MAY 4, 1918.

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Patented July 6, 192T? Z SHEETS-SHEET 2 mm? r225? Erna! JEEUbEE'L-L j v HZZUPUEy EIMIL JACOBSEN, OF CHICAGO, ILLINOIS, ASSIGNOB TO AUTOMATIC ELECTRIC GOMPANY,-OF QHICAGO, ILLII TOIS, A CORPORATION OF ILLINOIS AUTOMATIC TELEPHONE. SYSTEM.

Specification of Letters Patent.

Patented July a, rose.

. Application filed May a, 1918. Serial no. 232,616.

My invention rglatesio automatic telephone systems, and more particularly to.

telephone systems comprising a; main exchange and a pluralit of private automatic branch exchanges. t is often desirable to have two or more grou s of trunk lines terminating in one'level an automatic switch, which switch maybe operated in response to two digits to select one ofsaid groups and will automatically select a trunk line in the selected groups. In the past where such anautomatic switch was 'used in which it was desired to select one or more groups of trunk lines in a single level and to then automatically select a trunk line in a selected group, and in which it was also desired to have certain levels undivided and to operate .the switch to select idle trunks in that level it has been necessary to send two digits to the switch to first pick out a level and then to pick out a group in the level where the level was dividechand also it has been necessary to send two digits to operate the switch to select an idle trunk in a level in which the trunks are not divided into groups, while in reality it would be much better to send only one digit and have the switch automatically cut in asa selector to select the trunks. It will be seen that in this former method an extra digit was required of a calling-subscriber when using the switch as a straight selector repeater with a level undivided.

Among the objects of my invention therefore to provide an improved automatic switch'of this type which in response to one digit will automatically select a trunk line in a level having only onegroup of trunk lines, and in response to two digits will automatically select a trunk line in a level having twoor more oups of trunk lines. These and other ob ec ts of my invgntion will be more fully described hereina ter. I

In the drawin I have shown acalling substation A (Flg. 1) having access to selector D through the medium of the well sistance which in addition to stoppin are known rotary type of line switch C. The selector D 15 of the well known Keith, Erickson ty e similar to that shown in U. S. Let-' ters atent #815,321 granted March 13, 1906, to Keith, Erickson and Erickson, except that the side switch has been omltted and the circuits rearranged to operate over two sides of a calling line in series.

Accessible to the selector D are a number ofselector repeaters E (Fig. 2). The general construction of the selector repeaters E is practically the same as that of selector D, the circuits and mode of operation, however, being somewhatvdifl'erent as it is necessary thatthis selector be provided with means for repeating impulses over a seized trunk to another exchange in 'order to extend the call through that exchange, also I the provision of two private contacts for each trunk and two testing wipers for, the

switch. I have shown two levels of contacts 57 and 58for the private wipers in the I bank to which the selector E has access. The level of contacts'57 is divided into two groups, one group of five contacts bein connected to trunk lines in one branch exc ange and the last five contacts being connected to trunk lines in another branch exchange.

The first contact accessible to the testwiper in a level having two or more groups of trunks is connected to ground through a rerotation of the wipers'will prepare a clrcuit so that the wipers will be rotated in response to impulses delivered by the calling line to select the desired group. The level 58 is not provided with this ground on the first contact and is not divided into groups, all

the trunks in this level being connected to the same branch exchange. r

I will now describe the operation of the switches in detail when a call is made by the subscriber A.

When the subscriber at substation A removes his receiver a circuit is closed at the switch hook springs for the line relay 3 of the switch C in series with the line circuit. Relay 3 energizes to close a circuit at springs 4 including switching relay 5 and rotary magnet 6 in series and at the same time to close a circuit at springs 7 for the magnet 6.

to the private wi 'er 8. Suppose that the trunk line upon w ich the switch C is resting is busy and a ground is present on the private contact corresponding to thls trunk,

the

then this ground will shunt the high resistance relay 5 and energize the rotary magnet 6 to step the wipers 8, 9 and 10 to the contacts of the next trunk line. If this trunk line is busy the rotary magnet will again energize and the operation will continue until an idle trunk is reached, at which time there will be no potential present at the contact which the private Wiper 8 meets. Relay 5 will no longer be shunted out and will immediately energize over the series circuit hereinbeiore traced, to extend said line circuit to the trunk leading to selector D by means of the springs 12 and 13.

Relay 5 upon energizing, closes a circuit for the line relay 14 ofswitch D, in series with the line circuit and wipers 9 and 10. Relay 14 upon energizing, closes a circuit at springs 15 and 16 for the slow release relay 18. Relay 18 energizes to prepare a circuit at springs 19 and 21 for relay 22 and vertical magnet 23 in series, opens a point at springs 19 and in the circuit of the release magnet 24, and closes a circuit at spring 25 to hold the relay 5 of switch C energized. When a series of impulses corresponding to the first digit of the called number are relay 14 operates to open and close the circuit 6f magnet 23 at springs 19 and 21, a corresponding number of times, to thereby step t e wipers 26, 27 and 28 to a desired level of the banks. Relay 22 is energized in series with magnet 23 and operates to close a circuit at springs 29 and 30 for the rotary interrupter relay 34. Relay 34 energizes to prepare a circuit for the rotary magnet at springs 32 and also closes a locking circuit for itself through springs 33. As soon as relay 22 deenergizes after the impulses cease a circuit for the rotary magnet 35 is closed at springs 29 and 31. Magnet 35 therefore operates to rotate the wipers 26, 27 and 28v onto the first contact of the selected level and opens the locking circuit of relay 34 at springs 36. Relay 34 then deenergizes and opens the circuit of magnet 35 at springs 32 which magnet decnergizes and prepares a new circuit for relay 34 to the private wiper 27. If the first trunk is busy the relay 34 will again be energized by the guarding potential at the contact associated with the wiper 27 to again close the circuit of the rotary magnet. Magnet 35 again operates to step the wipers to the next trunk. When the first idle trunk is reached no ground is present at wiper 27, and relay 37, which has heretofore been short circuited, is energized in series with relay. 34 from ground at springs 25. Relay 34 being of lowerresistance than relay 37 does not energize at this time. Relay 37, upon energizing, prepares a locking circuit for itself at spring which will be completed over wiper 27 from the next succeeding switch, also, by means of clivcred by the calling device 2 the.

springs 38' and 39, extends the line circuit to thetri'ink line leading to selector repeater E (Fig. 2) and thereby "closes a series circuit for the-line relay 41 of switch E in series with the line wipers 26 and 27 and the line circuit which has heretofore been traced. The slow release relay 42 is energized over a circuit closed by the operation of spring 43 ofline relay 41- which in turn places ground through springs 46 to the release tru'nkto thereby hold relays 5, and 37 of switches C and D respectively energized, opens a point in the circuit of the release magnet 47 at springs 48 and 50 and prepares a circuit for slow acting relay 51 and the vertical magnet 52 at springs 49 and 50. It has been stated that this selector repeater E has access to one group of trunksterminating in one level when operated'in response to a single series of impulses and that the selector has access to two or more groups of trunks terminating in another level when operated in response to two series of impulses. Also in addition to automatically selecting a trunk it is necessary for the selector to repeat the impulses from the calling device around the condensers 80 and 81 over a trunk line to the next switch in a branch exchange. 4

Assuming now that the subscriber at substation A desires to call into a branch exchange whose trunk lines terminate at contacts similar to 83 and 85 in the set of contacts in an undivided level. Now when a series of impulses corresponding to the second digit of the called number are transmitt'ed by the calling device 2 the line relay 41 operates to open and close the circuit of magnet 52 at springs 43 and 45 to thereby step the wipers 53, 54, 55 and 56 to the selected level of the bank. Relay 51 will energize in multiple with magnet 52 and will in turn close a circuit for the rotary interrupter relay 59 at springs 60 and 61 which has been previously prepared by the ofl normal springs 86. Relay 59 upon energizing, closes a locking circuit for itself at springs 63, through springs 66 and 86, and prepares a circuit for the rotary magnet at springs 64. Relay 51 upon deenergizing after this series of impulses completes the previously prepared circuit for rotary magnet 65 at springs 61 and 62, which magnet now operates to step the wipers onto the first contact of the elected level and opens the locking circuit of relay 59 at springs 66. Relay 59 will therefore deenergize and open the circuit of magnet 65 at springs '64, which magnet denerglzes and prepares a new circuit for relay 59 extending to the private wiper 55. Supposing the first trunk to behusy then relay 59 will be energized by the guarding potential at the contact associated with the wiper 55 and magnet 65 will again be operassociated with the wiper 55 at springs 68 and 78 and thence to the corresponding contact in the banks of all the selector repeaters which have access to the trunk line, thereby making the trunk busyto other calling subscribers; extends the line circuit by means of springs 71 and 72, with the windings of the impedance coil 73 and the upper winding 74 of electro polarized relay 76 in bridge thereof so that th line relay of the next switch which is connected to the selected terminals will be energized over a circuit including springs '71, springs 78 and 77, upper winding of relay 76, impedance coil 73, and springs 80'and 72. Relay 76 will not operate at this time it being constructed so that it will not operate when either winding 74 and assist each other which operation will be more fully described hereinafter. The next series of impulses delivered by the calling device 2 operates the line relay 41 in the well known manner to in turn open and close the extended trunk circuit at springs to thereby operate the line relay of the next succeeding. switch at the branch exchange. The operation of relay 41 will at this time have no effect on the magnet 52, as the circuit heretofore described was opened by the operation of relay 67, but will close the circuit of relay 51 at springs 49 and 50 as hereinbefore traced. Relay 51 uponenergizing during this series of impulses shorts out the resistances including the winding of relay 73 and winding 74 of relay 76 from the series circuit. Supposing that the calling subscriber A has operated the calling device the. number of times corresponding to the digits in the called subscribers number and that the called subscriber has answered by removing the 'receiver from its hook then battery is reversed by the connector switch over the trunk line in the well known manner from the branch exchange, which reverses the direction of current in winding 74 of relay 76. Relay 76 will now energize as windings 74 and 7 5 assist each other and the operation of spring 87 closes a circuit for relay 88 which in turn pperates to reverse battery to the calling When the calling subscriber replaces his receiver the circuit of his relay 41 is opened at the springs operated by the receiver hook.

Relay 41 denergizing opens the circuit of relay 42 at springs 43 and 44 and closes a point in the circuit of the release magnet'47 at springs 43 and 45. When relay 42 deenergizes it closes the circuit for magnet 47 at springs 48 and 50, also removes ground potential from the release trunk at springs 46 which opens the holding circuit of relays 5 and 37 of switches C and D respectively. Relay 37 of switch D upon denergizing closes a circuit of release magnet 24 at springs 11. The energization of magnets 24 and 47 of switches D and E respectively restores the wipers to normal position in the well known manner.

If all the trunks in a group in this undivided level are busy the wipers will be the group. I have shown the last two contacts of the groups of trunk lines in the private banks multipled together so that if this trunk is busy,the guarding potential on the lower contact associated with wiper 55, passes through the upper contact and wiper 54 thereby closing a circuit for relays 89 and 90 in series. Relay 89 upon energizing closes a locking circuit for itself and relay 90' at springs 92 and 93, interrupts a circuit for the operating magnet at springs 94 and closes the circult for the busy machine 96 at springs 95 to supply a busy tone tov the calling subscriber in the well known manner. The operation of relay 90 opens the circuit for the rotary interrupter relay 59 at springs 97 also opens thecircuit of magnet 52 at springs 98 and 99. The calling subscriber upon receiving the busy tone replaces the receiver on the switch hook, which in turn will calise the release of the apparatus as hereinbefore described.

Now supposing that the subscriber at substation A desires connection with a branch exchange whose trunk lines terminate in a level having more than one group of trunk lines. The wipers 53, 54, 55, and 56 are stepped to the selected level and automatically rotated to the first contact in the same manner as heretofore described. When the wiper 54 reaches the first contact in the elected level of two or more groups of trunk ,lines, an energizing circuit for relays 89 and also at springs 101 prepares. a holding circuit for itself. .The' next series of impulses transmitted by the calling device operates the line relay 41 in the usual manner which relay in turn opens and closes the circuit of rotary magnet 65 prepared by the operation of springs 99 and 100 to rotate the wipers to the first contact of the desired groups of lautomatically rotated to the last trunk in I Elli Lina trunk lines. Relay 51 energizes in multiple with magnet 65, and closes the holding circuit for relay 90 at springs 102 during this series of impulses. The calling subscriber will in the arrangement illustrated send either one or five impulses to the rotary magnet to step the wipers onto either the second 'or sixth set of contacts in this level. That is, as the first set of contacts are dead and are onily used to prepare an impulsing circuit, the first trunk of the first group will be connected to the second set of contacts and the first trunk of the second group will be connected to the sixth set of contacts. In either case whether the subscriber sends one or six impulses the wipers 53 to 56 will be rotated either one or six steps and come to rest on the second or sixth set. Now as the impulses cease, the relay 51 will fall back to open the holding circuit of relay 90. Relay 90 having no circuit at this time either through springs 102 or over the private wi er 54 will deenergize and prepare a circuit at springs 97 for the rotary interrupter relay 59 extending to the private wiper 55. The relay 59 now'operates in the same manher ,as previously explained when testing trunks in the level 58 to control the rotary magnet 65 to step the wipers on to find an idle trunk line in the group elected by the last digit. If the trunk lines in the elected group are all busy the wipers will be rotated only as far as the last trunk line in that particular group at which time the switch will operate in the same manner as when rotated to the last trunk in the level .58 to stop and give the calling subscriber a busy signal. It will be seen therefore that I have provided an improved mechanism and circuits therefor which makes it possible to have certain of the levels in the bank of a selector repeater divided into any number of small groups and at the same time the switch is so arranged that a call may be extended through said switch to one of the .regular trunk lines, which are arranged in undivided levels, without having to call an extra digit to step onto the first set of contacts of that group.

This arrangement will be very valuable where it is desired to keep the apparatus standard with regard to calls over the regular trunks and where the addition of an extra digit for regular calls in order to give the selector repeater access to one level having more than one group of trunks, is not advisable.

Having fully described and ascertained my invention what I consider to be new and desire to have protected by Letters Patent will be pointed out in the appended claims.

What I claim as my invention is: v

1. In a telephone system, an automatic switch, contacts accessible to said switch,

ascents means for operating said switch and for causing. it to rotate over said contacts, ground connections for certain of said contacts, means in the switch controlled by the ground on said contacts when connection is made therewith, for stopping the rotation of said switch, and means for then operating the switch in response to a series of impulses corresponding to a digit of the called number before the switch is released.

2. In a telephone system, an automatic switch, groups of trunk lines accessible to said switch, certain of said groups, being further divided into sub-groups, means for operatin-gthe switch in response to a single digit of a called number to select an undivided group of trunks, and for then causing the switch to automatically rotate over the saidftr'unk lines in search of an idle trunk, and means for operating the switch in response to two digits of the called number to select a divided group of trunks, and to cause the switch to automatically rotate over the said trunk lines to pick out an idle trunk line in the desired sub-group.

3. In a telephone 'system, an automatic switch, groups of trunk lines accessible to said switch, certain of said groups being further divided into sub-groups, means for operating the switch to select an undivided vgroup of trunks, and for causing the switch 4. In a telephone system, an automatic switch, groups of trunk lines accessible to said switch, certain of said groups being further divided into sub-groups, means for operating the switch to select a desired group, of trunks, means controlled solely from the trunk lines for causing the switch to automatically rotate over the said trunk lines in search of an idle trunk when the call is extended to an undivided group, and means for operating the switch in response to one digit of the called number to select a divided group of trunks, and in response to-a second digit to pick out a desired subgroup.

5. In a telephone system, an automatic switch, groups of trunk lines accessible to said switch, certain of said groups further divided into sub-groups, means controlled by a calling subscriber for-operating said switch in response to one digit of a called rsaaoas digit to select a divided group of trunks and in response to another digit of a called numher to further operate the switch to select a desired subscribers group in the group, and means for then causing said switch to auto matically select an idle trunk in the selected sub. group. i

6. In a telephone system, an automatic switch, groups of trunk lines accessible to said switch, certain of said groups being :turther divided into sub-groups, apair of test Wipers for said switch, means for operating said switch in response to a single digit of the called line to bring said wipers into association with any one ofsaid groups of trunk lines, means controlled over one of said test wipers, when an undivided group is selected, for causing said switch to automatically rotate to test the trunk lines of that group, means controlled over the other test wiper for preventing the automatic rotation of the switch when a divided group is selected, means for then further operating said switch to select a desired sub group in this divided group, and means controlled over said one test wiper for then operating the switch to testthe trunk lines of the selected sub group. 7 I

7. In a telephone system, an automatic switch, a directively operable primary magnet and a combined directively and auto matically operable secondary magnet for controlling the operation of said switch, means for in one instance operating only the primary magnet by impulses corresponding to a digit of the called number, and for then automatically operating the secondary magnet to extend a call through said switch,

[automatically operate to select a trunk line in an undivided group, and means for operating both primary andsecondary magnets ating said switch to select adesired level, automatic means for then causing the switch to automatically rotate if'the selected level is undivided, a test contact individual to a divided level and means controlled from said test contact when connection is made therewith for preventing the automatic rotation of the switch when a divided level is selected.

10. In a telephone system, an automatic switch, a plurality of contacts, arranged in levels, accessible to vsaid switch, certain of said levels having trunk lines of a single group connected therewith and other of said levels having trunk lines of a plurality of groups connected therewith, means for operating said switch to select a desired level, automatic means for then causing the switch to automatically rotate it the selected'level is undivided, a test contact individual to a divided level and means controlled from said test contact when connection is made therewith for preventing the automatic rotation of the switch when a divided level is selected and means for then again operating the-switch to select a sub-group of the contacts in this selected level.

11. In a telephone system, an automatic switch, a plurality of contacts, arranged in levels, accessible to said switch, certain of said levels having trunk lines of a single group connected therewith and other of said levels having trunk lines of a plurality of groups connected therewith, means for operating said switch to select a desired level, automatic means for then causing the switch to automatically rotate it the selected level is undivided, a test contact individual to a divided level and means-controlled from said test contact when connection is made therei with for preventing the automatic rotation of the switch when a divided level is selected, means for then again operating the switch to select a sub-group'of the contacts in this selected level, and means for then causing the switch to automatically rotate to select an idle trunk in the selected sub-group. 7

12. In a telephone system, an automatic switch, trunk lines accessible thereto divided into groups, means forautomatically operating said switch to find. an idle trunk line in any of said groups, means in the switch responsive to a single digit of a called number to pick out certain levels of said switch and to start the automatic rotation of the switch to select a trunk in that group and for operating the switch in response to more than one digit of a called number to select other groups of said trunks and to start the automatic rotation of the switch to select trunks in any of those groups.

13. In a telephone system, an automatic switch, trunk lines accessible thereto divided into groups, a magnet in the switph responsive to the impulses of a singledigit of a called number to step the switch into connection with one of a certain group of said trunk lines, and another magnet operable when connection is made with the first trunk line for rotating the switch automatically over said trunk lines in search of an idle trunk, a relay operated when the switch connects with the first contact of another group in response to said first digit for preeas es venting said automatic rotation, said other magnet then responsive to impulses of a second digit to select another group of trunk lines or to impulses of another digit to cause the automatic rotation of the switch in the group before which the switch is standing.

Signed by me at Chicago, Cook county, State of Illinois, this 27th day of April, 1918.

E'MIL JACOBSEN. 

